Sometimes I find some parts on German ebay. I think most can’t be purchased as individual from the original suppliers and are often expensive either.
Obviously most work with the state and schools and broadcasters and stuff is bought in dozens for the students.
Most famous was maybe the MFA (8085 rack style) from the BFZ Essen.
The one pictured with an 8085 is from hps systemtechnik. There’s also an additional board. Currently they use 80C535 and PIC. There are also analog and digital boards. Here’s a PDF
For different jobs there’s different hardware. For automation probably most using Siemens S7 PLCs. Several companies make stations for that with additional application cards. Some even from cardboard. Most recently I found a small washing maschine card with error simulation. Very funny and interesting. But one needs a PLC, the station and the analog extension. The manual can’t be purchased separately yet.
I also found PCBs with a paper labeled front which a student has to solder himself. I found official material from the examination committee IHK with schematics, Gerber files and some files (HEX and ELF). For different jobs profiles (click on +Abschlussprüfungen to show the files), some examples for computer jobs here
Elektroniker/-in für Informations- und Systemtechnik - IHK Region Stuttgart
Elektroniker/-in für Automatisierungstechnik - IHK Region Stuttgart
all jobs listed here (in German)
Berufe A bis Z - IHK Region Stuttgart
I wonder how this is done in other countries in earlier times and now. Maybe some even use German parts?